diff --git a/ggml/include/ggml-backend.h b/ggml/include/ggml-backend.h
index d0c7e5a1be..b6f7373980 100644
--- a/ggml/include/ggml-backend.h
+++ b/ggml/include/ggml-backend.h
@@ -169,7 +169,7 @@ extern "C" {
         // device type
         enum ggml_backend_dev_type type;
         // device id
-        //   for PCI devices, this should be the PCI bus id formatted as "domain:bus:device.function" (e.g. "0000:01:00.0")
+        //   for PCI devices, this should be the lower-case PCI bus id formatted as "domain:bus:device.function" (e.g. "0000:c1:00.0")
         //   if the id is unknown, this should be NULL
         const char * device_id;
         // device capabilities
diff --git a/ggml/src/ggml-cuda/ggml-cuda.cu b/ggml/src/ggml-cuda/ggml-cuda.cu
index 8d21b2267f..925a9ffe04 100644
--- a/ggml/src/ggml-cuda/ggml-cuda.cu
+++ b/ggml/src/ggml-cuda/ggml-cuda.cu
@@ -5434,6 +5434,9 @@ ggml_backend_reg_t ggml_backend_cuda_reg() {
                 char pci_bus_id[32] = {};
                 CUDA_CHECK(cudaDeviceGetPCIBusId(pci_bus_id, sizeof(pci_bus_id), i));
                 dev_ctx->pci_bus_id = pci_bus_id;
+                for (char & c : dev_ctx->pci_bus_id) {
+                    c = std::tolower(c);
+                }
                 dev_ctx->op_offload_min_batch_size = min_batch_size;
 
                 ggml_backend_dev_t dev = new ggml_backend_device {